In conventional telecommunications signaling networks, signal transfer points terminate SS7 signaling links that carry signaling data and no bearer data. Each signaling link consists of bi-directional time division multiplexed channels. In conventional networks, the signaling links terminated by signal transfer points are typically 56 kbps or 64 kbps DS-0 links.
In order to transfer signaling information across long distances, many DS-0 channels may be multiplexed into a single high-speed link, such as a DS-1 or E1 link. A DS-1 link uses a T1 carrier, which operates at 1.544 Mbps. Thus, a DS-1 link consists of 24 64 kbps DS-0 channels. An E1 link uses a carrier that operates at 2.048 Mbps. Thus, an E1 link consists of 32 64 kbps DS-0 channels.
Since conventional signal transfer points are incapable of processing such high-speed links, external channel banks are required at each STP in the network. External channel banks include multiplexers and demultiplexers that multiplex and demultiplex a T1 or E1 link that carries signaling information to and from a signal transfer point. FIG. 1 illustrates a conventional signal transfer point with external channel banks. Referring to FIG. 1, signal transfer point 100 terminates DS-0 channels DS-01-DS-024. Similarly, since signaling links are bi-directional, signal transfer point 100 also outputs DS-0 channels DS-01-DS-024.
Since DS-0 signals are transported by high-speed T1 carriers, channel banks 102 and 104 are required to multiplex and demultiplex channels to be processed by signal transfer point 100. More particularly, channel bank 102 demultiplexes a DS-1 signal carried over a T1 carrier into 24 DS-0 channels, and channel bank 104 multiplexes 24 DS-0 channels into a DS-1 link for transmission over a T1 carrier.
As illustrated in FIG. 1, channel banks 102 and 104 are hardware components external to STP 100. Using external channel banks is undesirable because such equipment consumes space in telecommunications facilities and requires additional cables to carry the individual channels to and from the signal transfer point.
In order to reduce the need for external channel banks, signal transfer points that directly terminate some types of high-speed TDM channels have been developed. For example, the assignee of the present application has developed an E1 card capable of terminating an E1 signals at a signal transfer point. The E1 card receives an E1 signal from an external network, processes 8 of the 32 DS-0 channels on the card, and forwards the remaining channels to a downstream card for processing. Dividing the processing of the E1 signal among multiple cards allows low-speed hardware to be used to process a high-speed signal.
While the above-referenced E1 card scheme is capable of processing a high-speed signal at a signal transfer point, that solution does not provide a way for handling voice or bearer data at a signal transfer point or for filling an outbound link with data from multiple sources. These capabilities can be important within a carrier's network in order to maximize utilization of expensive T1 or E1 facilities. Accordingly, there exists a long-felt need for improved methods and systems for filling channels in an outbound communications facility at a signal transfer point with data from different sources.